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st: RE: Merge problem; missing observation


From   Nick Cox <n.j.cox@durham.ac.uk>
To   "'statalist@hsphsun2.harvard.edu'" <statalist@hsphsun2.harvard.edu>
Subject   st: RE: Merge problem; missing observation
Date   Thu, 9 Feb 2012 21:11:28 +0000

I don't know if this will make any difference but this certainly sounds like a 1:1 merge. 

Nick 
n.j.cox@durham.ac.uk 

Shubhabrata Mukherjee

  I have two files with the same # of observations but when I try to merge them somehow the merged dataset has one less observation. I checked that there was no observations which was dropped. What am I dong wrong here?

Thanks,

 -Joey

E.g.

#############

 File A

duplicates report snp

--------------------------------------
   copies | observations       surplus
----------+---------------------------
        1 |       691677             0
--------------------------------------


#############

 File B


duplicates report snp

--------------------------------------
   copies | observations       surplus
----------+---------------------------
        1 |       691677             0
--------------------------------------

#####################
merge file A with file B

merge m:1 snp using fileB, assert(match master) keep(match)

   Result                           # of obs.
    -----------------------------------------
    not matched                             0
    matched                           691,676  (_merge==3)
    -----------------------------------------


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